Lisa:Great job on this. I only had a couple of suggestions:
In viewmessages.tmpl, change this:
code:
{$ubbt_lang['TEXT_DELETE']}
To this:
code:
{$ubbt_lang['TEXT_SELECT']}
Then, in generic.php, add the following line:
code:
$ubbt_lang['TEXT_SELECT'] = "Select";
After this:
code:
$ubbt_lang['PM_EMAIL'] = "Email PM";
What this will do is to change the column header from "Delete" to "Select". I think this helps to avoid confusion since users might not figure out that they need to check the "Delete" box in order to email messages to themselves.

Changing it to "Select" still works for the "Delete Checked" button, so it shouldn't be confusing at all.
Hope this helps...